In motor vehicles, due to the increasing number of technical components, an optimization with regard to the installation volume is necessary, in order to be able to ensure generally the desired functionality by accommodating the components. For this reason, large-volume components for air conditioning, as known from stationary air conditioning units in the form of mixing chambers, flow guiding devices and vortexing devices, cannot be used in motor vehicles due to the space constraints.
An additional requirement for an air conditioning unit of a motor vehicle, which conditions a supplied air mass flow, optionally divides it and leads the individual air mass flows into different areas of the motor vehicle, consists in applying air mass flows at different temperatures to different air outlets of the air conditioning system, depending on position and function. As is known, the passenger compartment of motor vehicles has different comfort and ventilation zones. The air conditioning system of the motor vehicle offers a defined air quantity with a defined temperature for the respective zones, depending on the operating mode selected.
In the process, the supplied air mass flow is led over different heat exchangers, so that the air is cooled and dehumidified and also, if necessary, heated again and subsequently guided to the respective allocated zones via adjustable flaps into the passenger compartment. Here, the air is blown, for example, into the foot space as well as through openings in the dashboard into the passenger compartment and, in addition, it is guided via outlets directly to the windshield in order to keep it free of condensation or to defrost it.
In the case of air conditioning systems regulated on the air side according to the preamble, the air mass flow to be supplied to the passenger compartment is divided into two partial air mass flows, after flowing over a heat exchanger operated as an evaporator, by means of a flap, also referred to as temperature flap. By means of the temperature flaps and the different regulating mechanisms, the required temperatures of the air flows are set. In the process, one partial air mass flow is guided through a heating heat exchanger and heated. At the same time, the second partial air mass flow flows as cold air past the heating heat exchanger. The two partial air mass flows at different temperatures are subsequently mixed to reach the required target temperature and/or are separately conveyed further to the air outlets.
As is known, the flaps are adjusted by rotation or shifting. Depending on the rotation and/or shifting of the individual flaps within the air conditioning system, defined air quantities at defined temperatures are supplied to the individual zones in the passenger compartment. In the process, additional fittings are necessary within the air conditioning system, in order to ensure the desired air quantity distribution and temperature distribution. The mutually different temperatures of the air mass flows at the different outlets are referred to as temperature stratification. The so-called stratification fittings or channels tap cold or hot air mass flows from certain areas within the housing of the air conditioning system and lead them via channel-shaped designs to other areas in the housing. In contrast to the flaps, the stratification fittings are arranged rigidly and statically.
In EP 1 273 465 A1, an air conditioning unit for a motor vehicle is described. The air conditioning unit comprises a housing with an air inlet and air outlets, an evaporator and heating heat exchanger arranged in the housing, movable, in particular rotatable air guide elements in the form of temperature flaps as well as a static air guide element. The static air guide element is used for leading a portion of the heated air mass flow in a targeted manner from the heating heat exchanger to a first air outlet as well as for leading of a portion of the cold air mass flow, which has not been led through the heating heat exchanger, in a targeted manner to a second air outlet.
In EP 1 445 133 A2, an air conditioning unit for motor vehicles is disclosed. The air conditioning unit comprises a cold air passage, a hot air passage, and a deflection plate. The deflection plate is arranged at a site where the cold air passage and the hot air passage merge. The deflection plate is constructed with multiple cold air flow openings, which lead cold air from the cold air passage to a first outlet, and with multiple hot air guide channels oriented perpendicularly to the cold air flow openings, which lead hot air from the hot air passage to a second outlet and which are open on the outlet side.
The systems known in the prior art are characterized in that they comprise additional elements at a very high equipment expense, which require additional space and entail costs and also an additional installation effort as well as a corresponding maintenance effort. Moreover, when using the known flaps, it is moreover not possible to set the desired air quantity distribution and temperature distribution in each operating mode.
Moreover, the additional fittings, such as the mentioned hot and cold air channels of rigid and static design, which provide support for the temperature stratification only in certain setting ranges, lead to delimitations and constrictions within the housing and consequently elevated pressure losses in the air flow, which in turn leads to an elevated power demand and thus energy consumption as well as to a reduction of the efficiency of the air conditioning system and thus of the entire motor vehicle. Moreover, the maximum air quantities that can be achieved within the air conditioning system are reduced.